Marine craft propulsion system



y 7, 1966 M. w. BEARDSLEY 3,251,334

MARINE CRAFT PROPULSION SYSTEM Filed April 16, 1964 3 Sheets-Sheet 1 llVl/ENTOR MELV/LLE' n: BEARDSL E) A 7' TORNE Y y 7, 1966 M. w. BEARDSLEY I 3,251,334

MARINE CRAFT PROPULSION SYSTEM Filed April 16, 1964 3 Sheets-Sheet 2 P 20 g 4/ g? 4;

MELWLLE M BEARDSLEY ATTORNEY y 7, 1966 M. w. BEARDSLEY 3,251,334

MARINE CRAFT PROPULSION SYSTEM Filed April 16, 1964 3 Sheets-Sheei 3 ll 2a I/VVE/VTOR FIG. /4 MELWLLE' M BEARDSLE'Y ATTORNEY United States Patent 3,251,334 MARINE CRAFT PROPULSION SYSTEM Melville W. Beardsley, 40 Windward Drive, Severna Park, Md. Filed Apr. 16, 1964, Ser. No. 360,195

7 Claims. (Cl. 115-49) This invention relates to marine craft propulsion sys tems, and consists more particularly in new and useful improvements in a propulsion system for boats, hydrofoils, amphibious craft, and other types of vehicles, and is especially designed for high speed travel over a surface of water of any depth with a maximum of propulsive efficiency.

Conventional water propellers and hydrojet propulsion units, when operated at high speed, sufier large losses in efficiency and require a definite depth of water for operation. With propeller driven craft, operation is limited to depths sutficiently great to prevent propeller contact with the bot-tom, and with hydrojets, even though the required depth is significantly less than necessary for propeller operation, a substantial depth is required for satisfactory operation.

The primary object of the present invention is to provide a marine propulsion system which will overcome the problems and disadvantages encountered at high speeds by water vehicles employing conventional water propulsion means and one which will achieve greater overall propulsive efliciency at high speeds.

Another object of the invention is to provide propulsion means which will minimize or eliminate cavitation at high speeds.

Another object is to provide propulsion means for marine craft which is efiective for operation over a body of water of any depth.

Still another object of the invention is to provide a propulsion system which is adapted for the operation of water craft in areas of heavy marine vegetation.

A further object of the invention is to provide a propulsion system capable of propelling amphibious vehicles over dry land, as well as over water.

A still further object is to provide a propulsion system which may be integrated into a boat design in such a manner that resistance is reduced and overall propulsive efficiency increased.

Another object of the invention is to provide a single propulsion system adaptable to high speed amphibious vehicles for all operating conditions.

Finally, it is an object of the invention to make possible high performance amphiobious vehicles of increased utility, less complexity, and lower cost.

With the above and other objects in view which will appear as the description proceeds, the invention consists in the novel features herein set forth, illustrated in the accompanying drawings, and more particularly pointed out in the appended claims.

The invention comprises a propulsion system employ ing water as the working medium, said medium being accelerated rearward to thereby cause a consequent reaction which provides a forward thrust for the vehicle. This fundamental principle, of course, is similar to all continuous-medium propulsion devices, such as the conventional water propeller. However, the operation of the present invention differs from that of a conventional water propeller in that it acts upon the surface layer of 'water instead of on a homogeneous stream tube of water at some depth below the surface. Two propulsion systems of different types will provide the same thrust if, having equal efiiciency, they effect the same acceleration on equal mass flows of fluid. For example, the thrust of a conventional propeller giving a rearward acceleration of 10 feet per sec. per sec. to a cylindrical stream tube" having a cross-sectional area of one square foot will be equalled by the thrust of a propulsive system embodying the present invention which also gives a rearward acceleration of 10 feet per sec. per sec. to a stream tube'of 1 square foot cross-sectional area, although this stream tube cross-section may be 5 feet wide by 0.2 feet in depth. The stream tube velocity is assumed to be the same in each case.

Referring to the accompanying drawings in which numerals of like character designate similar parts throughout the several views:

FIG. 1 is a diagrammatic view in side elevation, il-

lustrating theprinciple of operation of the invention and the fiow conditions which provide vehicle propulsion;

FIG. 2 is a schematic view in side elevation, illustrating the adaptation of the present invention to a track propulsion unit;

FIG. 2a is a detail taken on line 2a--2a of FIG. 2, and illustrates one planform of a blade arrangement which may be advantageously embodied on the water engaging surface of the propulsion element per se;

FIG. 3 is a side elevation of a boat equipped with the propulsion system of the invention, located at the stern of the hull;

FIG. 4 is a top plan view of the same;

FIG. 5 is a side elevation illustrating another boat i embodiment of the invention wherein the propulsion system is'located in a forward position;

FIG. 6 is a sectional view taken on line 6-6 of FIG. 5;

FIG. 7 illustrates the application of the propulsion system of the invention to a hydrofoil-supported craft;

FIG. 8 illustrates an embodiment of the invention for the propulsion of an air-cushion type vehicle;

FIG. 9 'is a diagrammatic side elevational view showing an embodiment of the invention adapted for amphibious craft;

FIG. 10 is a plan view of the structure shown in FIG. 9;

FIG. 11 is a fragmentary side elevational view of a tire design for dual purpose embodiment in an amphibious craft to provide thrust for,travel over land or water;

FIG. 12 is a sectional view taken on line 1212 of FIG. 11;

FIG. 13 is a fragmentary plan view of the tire tread shown in the previous figures; and

FIG. 14 is a fragmentary sectional view of the tread profile taken on line 14'14 of FIG. 13.

Referring first to FIG. 1, which diagrammatically illustrates the principle of operation of the invention, 20'

represents a rotor or propulsion element which, in this instance, is in the form of a substantially cylindrical member having a series of substantially radially projecting blades 21 spaced around its periphery. This term blade is used broadly to include any element extending from the base circumference of the rotor. The blades 21 extend generally transverse of the periphery of the rotor with a slight angular inclination in the direction of counterclockwise rotation of the rotor 20 about the fixed axis 22, and the open areas 23 between blades adjacent to the tread center line should preferably be one to five times as great as the cross-sectional areas of the solid sections of the that it differs in the fundamental respect that the blades 21 are of such a depth and disposition that the rotor ac celerates only the surface layer 24 of the body of water, and it restrains this surface layer to prevent its escape upward over the accelerating members or blades. Thus, the blades-can be considerably shorter and can apply greater pressure and consequent higher acceleration without escape of a portion of the water being acted upon. Because of this significant difference, the propulsion system of the present invention is adaptable to high speed water vehicles for which a paddle wheel would be completely inadequate. As the rotor 20 turns in counterclockwise direction about the axis 22, located with the indicated height relation to the water surface 25, it rotates with a tangential blade tip speed of V which is greater than the forward velocity V of the vehicle it propels. Considering the movement of the surface layer of water as if the axis 22 were fixed, the vector diagram shown indicates the velocity, V /w of the blade tip relative to the water surface 25. At the bottom of the blade travel, the difference between the horizontal component of the blade tip velocity and the water velocity is at its maximum, and this difference, V V =AV, is approximately the magnitude of rearward acceleration given the mass flow of the water layer acted upon to provide forward thrust reaction.

As shown in FIG. 1, as each blade 21 enters the Water, it shears off lamina which. is retained between the blades in the successive spaces 23 as it is accelerated rearward. Since these increments of water, indicated at 26, have an absolute velocity (AV) when the blades 21 are at the bottom of their travel, the water increments merge into a sheet 27, separating from the blades 21 as they move upward in their rotation about the axis 22. This separation may be considered as caused by centrifugal force on the increments 26 due to their rotation about instantaneous positions of the axis 22, or as due to the more fundamental rule that a body maintains a given velocity unless acted upon by an external force. Although there is a net upward pressure force acting on the increments 26 immediately posterior to the point of discharge, this force is so small as to be relatively inconsequential at this point.

As the discharged sheet or stream 27 moves farther rearward, however, the upward pressure has increasing influence so that with the addition of friction forces, the sheet stream 27 is given an upward curving path. If unrestrained, it would erupt above the surface level to a height determined by its kinetic energy, and essentially form a wave traveling along behind a rotor 20.

In order to contend with this condition, it has been found beneficial to employ a surface, such as a portion of a hull bottom, or a foil, or vane, 28, supported by any suitable means, located behind the rotor 20. This surface has its leading edge 29 immediately adjacent to the path of the rotating blade tips and disposed at a lower level than its trailing edge 30. This surface 28 not only prevents inconvenient spray and discharge wave height, but increases the effective thrust and efficiency of the device, particularly in starting from a stationary position. The flow of the upward moving sheet stream 27, when restrained by the vane or foil 28, creates a pressure on its bottom surface, and since this pressure force has a forward component, it provides additional thrust. Thus, the utilization of the fiow after discharge, as in this propulsion system, achieves greater thrust and efliciency than a comparable propeller with which the fiow energy is dissipated in useless friction.

As will hereinafter appear, it has also been found desirable, in some instances, to employ a surface such as a planing surface, a foil or vane, forward of the propulsion rotor as a means of controlling the depth of immersion at which the propulsion rotor operates and for minimizing adverse effects of rough water. A forwardly located vane surface is also helpful in starting and accelerating to ve- F=MAV =dA V (V V where the symbols are:

' AV=Increase in rearward velocity d :Mass density of fluid medium A :=Area of cross-section of free stream acted upon V =Velocity at discharge from propulsive means V =Velocity of free stream Refering to FIG. 1, the free stream cross-sectional area of the fluid acted upon is:

A bh

where b=width of fluid stream (and rotor) lz depth of free stream If the fluid acted upon is contained between the reaction blade 21, it will have essentially the same velocity during entrainment as the blades, and this velocity is also essentially equal to the discharge velocity V Therefore, for continuity of flow, h bV =h b V where h =effective blade height and Substituting for A in the basic thrust equation, the thrust is:

To give an idea of order of magnitude of thrust produced by this propulsion means, calculation by the above equation gives a thrust of approximately 1000 lb. per sq. ft. of blade face area at a vehicle speed of 45 m.p.h. and a velocity ratio,

This thrust is produced with a calculated efficiency of OVBI At high speeds this method of propulsion has a significant advantage over a propeller in regard to cavitation, which, as a rough generalization, is due to speed. Thus, whereas the velocity of a propeller blade relative to the water is the vector sum of its rotational and forward velocities, the relative velocity of the blades of a propulsion means according to the invention is essentially the difference between the blade-speed and the forward speed. Hence, whereas the velocity of a conventional propeller blade tip will probably be greater than 100 ft. per sec. at a forward speed of 50 m.p.h., a propulsion means according to this invention might have a blade speed relative to the water of about ft. per sec., or probably less, for the same general conditions. In addition, a detailed analysis shows that cavitation would have little adverse effect on the performance of a propulsion means of the invention because this means does not rely on low pressure areas to move the fluid, and all forces are more directly translated into thrust than is the case of forces on 'a conventionally pitched propeller blade.

This method of propulsion, according to the invention, is also superior to conventional propellers or hydrojets for operation in areas of heavy marine growth because, operating on the surface, it tends to push surface vegetation down without tearing; whereas, a propeller tends to shear and wrap it up, and the hydrojet sucks vegetation against its inlet screen so that water flow and thrust is greately restricted.

Referring again to FIG. 1, it is obvious that the propulsion means of this invention can apply tractive force on dry ground, where the rotor 20 serves as a wheel. Hence, it is also obvious that a boat or other vehicle employing this invention may be operated over water of any depth without fear of the serious damage which may be incurred when a conventional propeller strikes the bottom or a submerged obstacle. I

As before indicated, due to its unique characteristics, the propulsion system of this invention may be employed to propel vehicles over both water and land. As seen in FIG. 2, this can be accomplished with a propulsion rotor or track 31 having an elastomeric surface provided with an endless series of blades 21, generally similar to those shown in FIG. 1. The track 31 travels over the periphcries of a driven wheel 32 powered by any suitable means,

and preferably located forward on the vehicle, and preferably two properly spaced, rearwardly located bogies 33 and 34, the latter being located at the stern end of the vehicle substantially in a position such as would be occupied by the propulsion rotor 20 of FIG. 1. As in the case of the rotor 20, a suitable surface, such as a portion of a hull bottom or a foil or vane 28 is provided aft of the propulsion track and serves as a wave and spray prevention surface.

It will be apparent that there are two significant differences between track propulsion according to this invention and previous track propulsion apparatus. The present invention, as before stated, employs the wave and spray prevention surface 28 and it also operates with generally less track immersion. With this invention, the water level would generally be below the level indicated by line 35 in FIG. 2. The blades 21, in this instance, are uniformly spaced and aligned substantially transversely to the direction of track movement, and while they may have various planform patterns or shapes, that shown in FIG. 2a represents one example. In this view, which is taken looking upward at the track in the rearward moving segment of its path, it will be seen that the substantially V- shaped diverging blades cause at least a portion of the water acted upon to be discharged laterally as the lower run of the track moves rearwardly in the direction of the arrow in FIG. 2. It has been found that a broader range of eflicient operation may be achieved by the blade planform shown in FIG. 2a.

Referring to FIGS. 3 and 4, B represents a boat hull propelled by an apparatus embodying this invention. In

this embodiment, the propelling rotor 20 is located at the stern of the boat hull and preferably driven by an inboard engine 39, any suitable means, such as belts or chains 37 running over sprockets 38 which are coaxial with the rotor 20, being employed as the power transmission means. The rear vane 28 may be secured in place by suitable arms 36 attached to the stern of the boat B. A forward located rudder 40 may be employed for steering, although a stern rudder or differential speed operation of two adjacent propelling rotors 20 could be employed.

This propulsion arrangement provides a greater overall efliciency than a propeller of otherwise equal efficiency because it accelerates the boat hull boundary layer to provide thrust. Since the retarded boundary layer enters the propulsion rotor 20 with less than free stream velocity, its discharge velocity and'resulting energy loss is less than if the fluid had entered the rotor or propeller at free stream velocity.

A further example of a boat embodiment of the invention is illustrated in FIGS. 5 and 6, where it will be seen that two laterally spaced propulsion rotors 20 and 20:: are provided forward of the boat B. FIG. 5 shows the boat in high speed operating condition, in which case the weight may be supported on the rotors 20-20:: forward, and on the bottom aft planing surface. With this arrangement, the overall boat performance is improved by the substantial reduction of wave drag.

It may be noted that the structures shown in FIGS. 3-6 are only two examples of possible arrangements of a boat propulsion mechanism according to the invention. For instance, propulsion rotors may be installed both fore and aft so that at high speeds the boat hull could be completely-clear of the water.

FIG. 7 illustrates the application of the propulsion system of the invention to a hydrofoil-supported craft. The propulsion rotor 20 is located forward and the craft is supported with the hull clear of the water at high speed by hydrofoil surfaces 41 forward of the rotor and near the stern. Steering by a stern rudder 42 or other steering means may be employed as previously indicated.

It is also contemplated within the spirit of this invention that the propulsion system described may be embodied in an air-cushion type vehicle, as shown in FIG. 8, which is purely diagrammatic for purposes of simplicity. The propulsion rotor 20 is driven by engine 39 and sprocket chain or belt 37 and is located aft on the body B. Preferably, both the rotor 20 and engine 39 are mounted on arms 43 attached to the vehicle body with a hinge connection 44. Air to provide pressure lift to the Vehicle is blown into the plenum 45 by a suitable fan 46 operated by a separate motor 47, a surrounding duct 48 directing the flow of air. surrounded by flexible walls 49. Since the propulsion rotor 20 is mounted on hinged arms 43, it is free to move vertically relativeto the vehicle body B, and thereby ride over irregular surfaces without transmitting vertical forces to the vehicle body. Thus, when proper materials are employed in the rotor construction, this means of propulsion can be used for travel over all types of surfaces, wet or dry, solid or soft.

It will also be understood that a rotor mounted on hinged arms as described above, or by other arrangements apparent to those skilled in the art, may be used with hydrofoil-supported craft or other water vehicle to provide for relative vertical motion. between 'the propelling rotor and the hull. This relative movement is sometimes desirable to enable the rotor to follow the water surface irregularities while the hull follows a more uniform path.

Properly designed rotor means for over water'propulsion may be employed in conjunction with conventional wheels and pneumatic tires which are used on land. Such an embodiment is illustrated in FIGS. 9-14 inclusive, where the invention is shown in combination with con- The plenum 45 is preferably laterally ventional automotive equipment. In FIGS. 9 and 10, a conventional automobile wheel and tire 50 is interposed between two bladed rotors and 20a, similar to the rotor shown in FIG. 1, the entire assembly being mounted for rotation about a common axis 22. and jointly driven by any suitable means.

The propulsion rotors 20-20a are of smaller diameter than the tire 50 so as to remain out of contact when traveling over dry ground. For water propulsion, immersion of the conventional tire 50 to the depth required for operation of the water propulsion rotors 20-2011 would create large resistance at high speed. Therefore, a wave making surface 51 is positioned directly in ad vance of the tire 50 to raise the water level to the rotor blades on rotors 2020a, and simultaneously reduce the drag of the tire 50.

Preferably, the wave making surface 51 is wedgeshaped as shown, and in advancing through the water it creates a bow wave 51a which spreads laterally as it moves rearward so that at its raised level it provides water for the rotor blades 21 to accelerate and thus generate thrust. Although wave drag is generated by the wave making surface 51, it is less than would have been caused by the immersed tire 50. It may be noted that this technique of controlling the local water level by use of a wave making surface can be employed with other arrangements when desirable. Although this one example is shown for illustration, it will be understood that other arrangements are within the scope of this invention, such as a rotor '20 laterally between two tires and advance surfaces causing a wave to rise between them to the rotor. Or single rib, low drag, tires may be used in either case without wave making surfaces.

For amphibious vehicles, the principles of the present invention may advantageously be embodied in One propulsion rotor which, without complicating appendages, can provide thrust for travel over land or water. In FIGS. 12-14 inclusive, a vehicle tire 54 with a special tread design is illustrated, and although this design may appear similar to the tread of some snow or tractor tires, it differs in certain important respects to provide efiicient water propulsion. Thus, there should be at least forty blades 21a which in plan are substantially V-shaped at the center, curving to terminate substantially perpendicularly to the sides, and spaced around the rotor or tire circumference. The open areas 53 (in the plane of rotation) between the blades adjacent to the tread center line should be one to five times as great as the cross-sectional area of the solid sections of the blades. In addition, these open flow areas between the blades should increase with the lateral distance from the tread center line to their diverging extremities, as clearly shown in FIGS. 11 and 13.

FIG. 14 shows the tread profile in the plane of rotation. It will be seen that in its preferred form the profile of the advancing face 55 should be substantially radial to the rotor and terminates at a distinct angle of 90 or less at the outer circumference 56. From this point rearward, the contour of the surface curves inward and reverses near the bottom of the recessed portion to give the greatest depth 57 adjacent to the basesof the following advancing face.

Since a tire of conventional width may not provide sufiicient blade width for efiicient water propulsion,.I have found it desirable to place two or more wheels and tires side by side on the same axle. With this arrangement, the distance between the tires should be approximately twice the distance between the blades of the tire tread at the side wall.

It will thus be apparent that full utilization of this invention makes possible high performance amphibious vehicles having the simplicity and the comparatively low cost of a single propulsion system.

From the foregoing, it is believed that the invention may be readily undersood by those skilled in the art without further description, it being borne in mind that numerous changes may be made in the details disclosed without departing from the spirit of the invention as set forth in the following claims.

I claim:

1. A propulsion system for vehicles traveling on a body of water, comprising a propelling element having a movable endless surface provided with a series of blades projecting outwardly therefrom and extending generally transversely between the lateral extremities thereof, said endless surface being disposed so that substantially only the blades thereof are immersed in a surface layer of said body of water, drive means for moving said endless surface to consecutively immerse said blades in said surface layer of water and cause them to move substantially horizontally therein, whereby increments of said surface layer are entrained and accelerated to produce a horizontal thrust reaction, a substantially horizontal surface disposed transversely aft of said endless surface with its leading edge disposed at a lower level than its trailing edge, and in contact with the surface layer of water acted upon by said blades to thereby prevent spray and utilize the flow of water after discharge to achieve increased thrust.

2. A propulsion system for vehicles traveling on a body of water, comprising a substantially cylindrical propelling element provided with a series of generally transversely extending blades projecting outwardly from the periphery thereof, said propelling element being disposed so that substantially only the blades are immersed in a surface layer of said body of water, drive means for rotating said propelling element about an axis transverse to the direction of vehicle travel to consecutively immerse said blades in said surface layer of water and cause them to move substantially horizontally therein, whereby increments of said surface layer are entrained and accelearted to produce a horizontal thrust reaction, and a substantially horizontal surface disposed transversely aft of said propelling element with its leading edge disposed at a lower level than its trailing edge and in contact with the surface layer of water acted upon by said blades to thereby prevent spray and utilize the flow of water after discharge to achieve increased thrust.

3. A propulsion system as claimed in claim 2, wherein said blades are angularly inclined in the direction of rotation of said propelling element, and the contours of the open areas between adjacent blades being substantially U-shaped in cross-section.

4. A propulsion system as claimed in claim 3, wherein said blades have substantially radial advancing faces terminating in relatively sharp tips, and their rear faces have curved surfaces extending from said tips to the bases of said blades.

5. A propulsion system for vehicles traveling on a body of water, comprising a propelling element having a movable endless surface provided with a series of blades projecting outwardly therefrom and extending generally transversely between the lateral extremities thereof, said blades being angularly inclined in the direction of rotation of said propelling element and the contours of the open areas between adjacent blades being substantially U-shaped in cross-section, said endless surface being disposed so that substantially only the blades thereof are immersed in a surface layer of said body of water, drive means for moving said endless surface to consecutively 9 10 line thereof are one to five times as great as the cross-sec- 2,091,958 9/ 1937 Brage 115-'-63 tional areas of the solid sections of said blades. 2,294,104 8/ 1942 Waddington 115 49 3,077,174 2/1963 Cockerell 11553 Refer n s Cl y the Exammer 3,141,436 7/1964 Cathers et al 114-67 X UNITED STATES PATENTS 5 FO G PATENTS 175,405 3/1876 Bardwell 115 49 472 93 12 1914 France 484,503 10/1892 Lord 115-49 5059,35; 139i Painton 11 9 MILTON BUCHLER, Primary Examiner. 68 1 0 Barnett 11 -49 95 4 7 4/1910 Fauber 115 53 l0 ANDREW FARRELL: Exammer- 1,710,869 4/1929 Farrell 115 49 

5. A PROPULSION SYSTEM FOR VEHICLES TRAVELING ON A BODY OF WATER, COMPRISING A PROPELLING ELEMENT HAVING A MOVABLE ENDLESS SURFACE PROVIDED WITH A SERIES OF BLADES PROJECTING OUTWARDLY THEREFROM AND EXTENDING GENERALLY TRANSVERSELY BETWEEN THE LATERAL EXTREMITIES THEREOF, SAID BLADES BEING ANGULARLY INCLINED IN THE DIRECTION OF ROTATION OF SAID PROPELLING ELEMENT AND THE CONTOURS OF THE OPEN AREAS BETWEEN ADJACENT BLADES BEING SUBSTANTIALLY U-SHAPED IN CROSS-SECTION, SAID ENDLESS SURFACE BEING DISPOSED SO THAT SUBSTANTIALLY ONLY THE BLADES THEREOF ARE IMMERSED IN A SURFACE LAYER OF SAID BODY OF WATER, DRIVE MEANS FOR MOVING SAID ENDLESS SURFACE TO CONSECUTIVELY IMMERSE SAID BLADES IN SAID SURFACE LAYER OF WATER AND CAUSE THEM TO MOVE SUBSTANTIALLY HORIZONTALLY THEREIN, WHEREBY INCREMENTS OF SAID SURFACE LAYER ARE ENTRAINED AND ACCELERATED TO PRODUCE A HORIZONTAL THRUST ACTION. 